Installation FAQ

Installation FAQ

What type of wire do you recommend for analog and digital audio?

Any modern installation will benefit from the exclusive use of digital audio wire for all analog and digital connections. Cable designed for digital audio has low capacitance and tight twist tolerances, and provides superior performance compared to analog cable.

What gauge of wire should I use with my D-sub 25 connectors?

The factory supplied crimp style AMP DB-25 mating connectors (Amp part number 1- 745496-8) are designed for 26 to 22 AWG wire.

What kind of punch blocks should I use for my digital audio installation?

The factory supplied crimp style AMP DB-25 mating connectors (Amp part number 1- 745496-8) are designed for 26 to 22 AWG wire.

How do I wire an unbalanced analog output to a balanced analog input?

Wire the unbalanced Hi to the balanced Hi, unbalanced Shield to the balanced side Lo and Shield.

How do I connect an unbalanced DIGITAL (SPDIF) CD output to a balanced AES input?

We suggest using a "balun" or format converter if possible, but if not available you can try connecting the CD (+) to AES in HI (+), connect CD (-) to AES in LO(-). Leave the AES input’s Shield connected at the console/card end only. This works because all of our AES inputs are transformer coupled. The impedance is not correctly matched, but this method will work in a pinch. The AES receiver will ignore the copy protect (SCMS) bit.

How do I connect a balanced AES digital console output to an unbalanced (SPDIF) input?

You must use an external AES to SPDIF converter.

Do I need to use a telephone hybrid with the phone module?

Yes. Phone modules are designed to interface via balanced analog line level connections to an external telephone hybrid. They are NOT intended to interface directly with the phone line. Doing so can result in damage to the console.

How do I make my ON-AIR light turn on when any of three microphones is open?

To do it this way with some consoles you need to add diodes in what is commonly called a wired-OR configuration. The orientation of the diodes will depend on the polarity of components and/or voltages in the external circuitry. But this is generally not necessary. On most of our consoles you can set the CR mute function for the desired mic channels and then wire your ON AIR light to the console’s ON AIR TALLY output, following the console-specific instructions as outlined in the console’s manual.

What are the logic outputs? Open collector? Relay?

Actually, neither. Almost all logic port outputs use a solid state switch, LH1522 or equivalent. This solid state switch works like a contact closure with about 10 ohms of resistance. It is also bi-directional, but we recommend that you wire ground side signals to the (–) terminals to keep the documentation and wired polarity consistent. You can switch a positive or negative voltage but be aware of the potential for dropping too much voltage across the 10 ohm resistance of the solid state switch and limit current to less than 100mA.

What type are the logic inputs?

All logic input ports are the photo diode side of a solid state switch. Logic inputs have a built in current limiting resistor that allows them to be controlled from +5 to +12vDC. Connect the external voltage to the (+) terminal and externally switch the ground side to activate the input.

Do I need to use an external DC power supply when wiring logic connections?

In most cases the answer is yes. Logic circuits are opto-isolated for maximum protection. Certain products, like the Wheatnet IP BLADEs and the Micro-Sat, do supply +5v and Ground.

What kind of “wall-wart” should I use to provide power to the logic inputs?

You can use an external “wall-wart” type DC power supply in the +5 to 12VDC range. Select a current rating based on the number of switches and LED’s (allow 10-15mA each). In most cases it makes sense to jumper the positive (+) side of the supply to all of the logic Input pins right at a punch block. Then externally switch the ground side of the “wall-wart” to the negative (-) logic Input port to activate it. Same with logic outputs, switch the GND side of the external supply. You can switch a positive or negative voltage but be aware of the potential for dropping too much voltage across the 10 ohm resistance of the solid state switch and limit current to less than 100mA.